Shear behaviour of infilled rock joints under different boundary conditions

Abstract

Recently use of commercial software for analysis and design of rock slopes, underground structures, mining projects, the foundation of any infrastructure projects, piles, etc. becoming more popular and widely used. But sometimes, this software has many limitations and cannot be used directly for finding out the strength and deformation behavior of rock joints when joints are subjected to external load because of the construction of different projects. Correct prediction of strength and deformation behavior of rock joints are important for safe, economical, and sustainable design. In the present work, strength and deformation behavior of unfilled and infilled rock joints have been studied numerically by using one of the commercial software Universal Distinct Element Code (UDEC) under different boundary conditions like constant normal stiffness (CNS) and constant normal load (CNL) boundary conditions. The numerical model results are compared with experimental results of the test performed on a physical model. The strength predicted by the numerical model is in close agreement with experimental results at low initial normal stress and for CNL boundary conditions, as the asperity degradation during shearing process is almost same throughout the test. The numerical model cannot correctly predict the shear strength of rock joints under CNS boundary conditions and at high normal stress for both CNL and CNS conditions, because of the degradation in the asperity during shearing process and available model dosenot consider this effect. Hence, UDEC code has been modified in the present study for its acceptability under both CNL and CNS boundary conditins and at high initial normal stress at CNL boundary conditions. A comparison of predicted value with experimental results indicated most of the prediction lies in the prediction bend of 95%.